On Fri, 8 Dec 2023, Daniel P. Berrangé wrote: > CC'ing the Xen folks > > On Thu, Dec 07, 2023 at 11:12:48PM +0000, Michael Young wrote: > > Builds of qemu-8.2.0rc2 with xen-4.18.0 are currently failing > > with errors like > > ../hw/arm/xen_arm.c:74:5: error: ‘GUEST_VIRTIO_MMIO_SPI_LAST’ undeclared > > (first use in this function) > > 74 | (GUEST_VIRTIO_MMIO_SPI_LAST - GUEST_VIRTIO_MMIO_SPI_FIRST) > > | ^~~~~~~~~~~~~~~~~~~~~~~~~~ > > > > as there is an incorrect comparision in include/hw/xen/xen_native.h > > which means that settings like GUEST_VIRTIO_MMIO_SPI_LAST > > aren't being defined for xen-4.18.0 > > The conditions in arch-arm.h for xen 4.18 show: > > $ cppi arch-arm.h | grep -E '(#.*if)|MMIO' > #ifndef __XEN_PUBLIC_ARCH_ARM_H__ > # if defined(__XEN__) || defined(__XEN_TOOLS__) || defined(__GNUC__) > # endif > # ifndef __ASSEMBLY__ > # if defined(__XEN__) || defined(__XEN_TOOLS__) > # if defined(__GNUC__) && !defined(__STRICT_ANSI__) > # endif > # endif /* __XEN__ || __XEN_TOOLS__ */ > # endif > # if defined(__XEN__) || defined(__XEN_TOOLS__) > # define PSR_MODE_BIT 0x10U /* Set iff AArch32 */ > /* Virtio MMIO mappings */ > # define GUEST_VIRTIO_MMIO_BASE xen_mk_ullong(0x02000000) > # define GUEST_VIRTIO_MMIO_SIZE xen_mk_ullong(0x00100000) > # define GUEST_VIRTIO_MMIO_SPI_FIRST 33 > # define GUEST_VIRTIO_MMIO_SPI_LAST 43 > # endif > # ifndef __ASSEMBLY__ > # endif > #endif /* __XEN_PUBLIC_ARCH_ARM_H__ */ > > So the MMIO constants are available if __XEN__ or __XEN_TOOLS__ > are defined. This is no different to the condition that was > present in Xen 4.17. > > What you didn't mention was that the Fedora build failure is > seen on an x86_64 host, when building the aarch64 target QEMU, > and I think this is the key issue.
Hi Daniel, thanks for looking into it. - you are building on a x86_64 host - the target is aarch64 - the target is the aarch64 Xen PVH machine (xen_arm.c) But is the resulting QEMU binary expected to be an x86 binary? Or are you cross compiling ARM binaries on a x86 host? In other word, is the resulting QEMU binary expected to run on ARM or x86? > Are we expecting to build Xen support for non-arch native QEMU > system binaries or not ? The ARM xenpvh machine (xen_arm.c) is meant to work with Xen on ARM, not Xen on x86. So this is only expected to work if you are cross-compiling. But you can cross-compile both Xen and QEMU, and I am pretty sure that Yocto is able to build Xen, Xen userspace tools, and QEMU for Xen/ARM on an x86 host today. > The constants are defined in arch-arm.h, which is only included > under: > > #if defined(__i386__) || defined(__x86_64__) > #include "arch-x86/xen.h" > #elif defined(__arm__) || defined (__aarch64__) > #include "arch-arm.h" > #else > #error "Unsupported architecture" > #endif > > > When we are building on an x86_64 host, we not going to get > arch-arm.h included, even if we're trying to build the aarch64 > system emulator. > > I don't know how this is supposed to work ? It looks like a host vs. target architecture mismatch: the #if defined (__aarch64__) check should pass I think. The following is a guess. Maybe Xen gets enabled because you have x86 Xen installed, and you are building QEMU for an aarch64 target (aarch64 emulation, running on a x86 host). So this is not meant to work for xen_arm.c and it would be better to disable xen_arm.c. On the other hand if you are trying to cross-build a QEMU binary meant to run on an aarch64 host, cross-building it on an x86_64 host, then yes this is meant to work and we need to figure out why the #if defined (__aarch64__) is not passing. > > Signed-off-by: Michael Young <m.a.yo...@durham.ac.uk> > > --- > > include/hw/xen/xen_native.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/include/hw/xen/xen_native.h b/include/hw/xen/xen_native.h > > index 6f09c48823..04b1ef4d34 100644 > > --- a/include/hw/xen/xen_native.h > > +++ b/include/hw/xen/xen_native.h > > @@ -532,7 +532,7 @@ static inline int > > xendevicemodel_set_irq_level(xendevicemodel_handle *dmod, > > } > > #endif > > > > -#if CONFIG_XEN_CTRL_INTERFACE_VERSION <= 41700 > > +#if CONFIG_XEN_CTRL_INTERFACE_VERSION >= 41700 > > This change is not correct > > We can see the upstream change was introduced in 4.17: > > $ git describe 2128143c114 > 4.16.0-rc4-967-g2128143c11 > > IOW, if we have 4.17 or newer these constants already > exist. If we have 4.16 or older, then we need to define > them to provide back compat. > > > #define GUEST_VIRTIO_MMIO_BASE xen_mk_ullong(0x02000000) > > #define GUEST_VIRTIO_MMIO_SIZE xen_mk_ullong(0x00100000) > > #define GUEST_VIRTIO_MMIO_SPI_FIRST 33 > > With regards, > Daniel > -- > |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| > |: https://libvirt.org -o- https://fstop138.berrange.com :| > |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| >
